In this work, we perform the above described analysis by computing all relevant non-renormalisable superpotential terms up to dimension eight, suppressed by powers of the string scale \(M_s^n\)  with \(n\le 5\) . We find a consistent set of VEVs, satisfying all D and F-flatness conditions up to this order, that give rise to the desired inflationary superpotential. It is important to emphasise that this set of VEVs describe the inflationary phase of the model, where in particular \(SU(5)\times U(1)\)  remains unbroken, and not the vacuum after the end of inflation. Indeed, the \(SU(5)\times U(1)\)  breaking occurs via a first order phase transition at a critical temperature which is lower than the inflation scale [1]}. As a result, the previous investigations of the particle phenomenology of the model remain in principle valid, since they describe the low energy vacuum.
